Perhaps I am fortunate that I haven't had a dust problem yet. I took the lens, as my only lens, to an outing in Utah and Arizona. Beautiful focus and color for the sandstone formations and the wide angle shot well for the landscapes.

Comparatively light

Doesn't come with a hood

The Canon EF-S 17-55mm f/2.8 IS USM lens is a fast lens with a maximum aperture of f/2.8, so you can use it to obtain a shallow depth-of-field or help with reasonable exposures in lowlight situations.

Yes, I would recommend this to a friend

Fast / accurate auto-focus

Weak Casing

As mentioned the lens is not a designated L grade lens and while this may not be really obvious based on the naked specifications it does show up with respect to its build quality.

For those buying a brand new Canon DSLR I would certainly recommend this over the standard kit lens. Faster glass is always worth the extra investment.

The Canon EF-S 17-55mm f/2.8 IS USM ($1,179 direct) is the top-end standard zoom lens for Canon APS-C cameras . Rebel D-SLRs are generally bundled with the EF-S 18-55mm f/3.5-5.6 IS II lens that, while quite sharp, has a relatively slow f-stop, often requiring you to use the camera's flash in dimmer...

Big; Expensive; Soft at 55mm

The Canon EF-S 17-55mm f/2.8 IS USM ($1,179 direct)  is the top-end standard zoom lens for Canon APS-C cameras. Rebel D-SLRs are generally bundled with the EF-S 18-55mm f/3.5-5.6 IS II  lens that, while quite sharp, has a relatively slow f-stop, often requiring you to use the camera's flash in...

This lens while being a bit expensive is worth every penny. While being extremely sharp and a constant 2.8 this lens is above any 17-50 lens out there in its class.

Constant 2.8 throughout the whole zoom range

Nothing

The optical quality of this lens is excellent. It allows you zoom from 17-55mm at a constant f2.8. Other zoom lenses will change the aperture but it can hold this constant as you zoom so it does not change your timing. The wide aperture makes it great for shooting parties indoors.

Consistent Output; Fast / accurate auto-focus; Nice Bokeh

Heavy

Nothing much to say. It's a great piece of glass that didn't get the "L" ring because it's EF-S, not because it's image quality lacks. Makes low-light photos easy with stabilization.